[jboss-jira] [JBoss JIRA] (JGRP-2167) Highest seqno is not resent nor recorded on receivers

[Bela Ban (JIRA)]

    [ https://issues.jboss.org/browse/JGRP-2167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13394440#comment-13394440 ] 

Bela Ban commented on JGRP-2167:
--------------------------------

{{Table.hr}} is not set because we receive only the seqno but not the message itself. If we set {{hr}} to (say) 500, then that would assume message number 500 has been received, and it won't get retransmitted. I don't want to change this logic as the change would be quite involved.

However, the last seqno is only resent by a member P when P is not sending any further messages (independent though of other members sending or receiving messages), so increasing {{resend_last_seqno_max_times}} will reduce (not eliminate) the chances of a last-multicast-dropped scenario. I suggest this as a workaround for now.

> Highest seqno is not resent nor recorded on receivers
> -----------------------------------------------------
>
>                 Key: JGRP-2167
>                 URL: https://issues.jboss.org/browse/JGRP-2167
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 4.0.1
>            Reporter: Radim Vansa
>            Assignee: Bela Ban
>             Fix For: 4.0.2
>
>
> I am investigating an issue in a stress test which leads me to a situation where in a TCP-based configuration a {{GMS[VIEW]}} is broadcast to all nodes, but it is not received by some of them. Soon after that there's a {{NAKACK2.HIGHEST_SEQNO}} that causes the node that is missing the last seqno to resend it, but the retransmit is not received either. There are no further retries, and generally no NAKACK2 activity until about 30 seconds later (when another node leaves after some timeout in the test).
> The receiver does not keep asking for retransmissions until it gets them, but it seems that {{NAKACK2.handleHighestSeqno}} doesn't update {{Table.hr}} (not sure if having highest received set to non-received msg would be legal, though).
> The sender uses default value {{NAKACK2.resend_last_seqno_max_times=1}}, and as there are no further mcast messages, the highest sent seqno does not change on sender. 



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